In a virtual reality (VR) interface field, computer stereo image creation technology basically employs a stereo display technique in which different image information is provided to user's left and right viewing to obtain a stereoscopic feeling. And, VR visual interface systems can be classified into a wide screen based stereo visual system for multiple users and a portable stereo visual system for personal users.
The wide screen based stereo visual system includes a projection module that outputs large scale images, a screen module on which the image is projected, and left and right viewing information separation modules that provide binocular viewings, e.g., a project-attached polarizing filter, stereo glasses, and the like. This system has been used for multiple users seeking to enjoy stereo image contents simultaneously in a VR environment such as a theme park or a widescreen stereo movie theater.
A typical example of the portable stereo visual system for personal users is a head-/face-mounted display (HMD/FMD) device. The HMD/FMD device has a construction that combines a micro display unit (for example, a small monitor, an LCOS (liquid crystal on silicon), etc.) with an optical enlargement structure similar to glasses, and receives image information of separate modules for each of the left and right eyes and two channels for a stereo visual display. This HMD/FMD device has been employed in environments that displays private information or in situations that require a high degree of freedom of body movement such as in a mobile computing.
In a stereo image creation technology, designated information is extracted from a user and used as an input value to create images reflecting an accurate stereoscopic feeling. Typically, an eye tracking technique that tracks a head motion or user's visual information is used to create accurate stereo images. In an ergonomics evaluation test, the motion of the user's pupils is tracked by using computer vision technology, or tracking elements are attached directly to the corneas of the eyes in a shape of contact lens in order to track the position of an object viewed by the user. There are commercialized technologies capable of tracking sight line direction with an accuracy of less than 1 degree by virtue of the above-mentioned techniques.
Each of today's visual interface units that visualize stereo image contents is designed to be suitable for used in individual environments that are restricted in their own ways. Therefore, these visual interface units have limitation when applying to a variety of stereo image contents, and large scale visualizing systems can provide information only at a single identical viewpoint to its users.
In a virtual space cooperation environment, it is improper for the existing stereo visual display units that output a single stereo image to utilize public or shared information and private information simultaneously. A hologram display device, which presents the natural sense of depth that each object occupies a space like a real object, has been recognized as an idealistic stereo image visual unit. However, such a hologram display device is mostly only used for special effects in movies or manufactured as a prototype in laboratories of the aerospace field, and it is yet to provide a satisfactory result for general users.
Meanwhile, due to the development of stereo image technology, a stereo image display device is being generalized in the form of a stand-alone platform. In the near future, mobile/wearable computing technology will be able to generalize a personal VR interface unit such as a see-through type FMD and also an interactive operation by mixing personal and public virtual information. Therefore, a new technology is required to naturally mix two or more stereo image space information types and present them to a desired user, but no corresponding result has been provided yet.